/*
 * @Descripttion: 
 * @Author: voanit
 * @Date: 2022-05-28 17:56:52
 * @LastEditors: voanit
 * @LastEditTime: 2022-05-28 18:03:37
 */
let obj={}
console.log(obj.person?.name);

obj.fn?.()

if(obj.fn){
  obj.fn()
}


// // callback&&callback()
// obj.callback?.()

function fn(callback){
  // if(callback){
  //   callback()
  // }
  // callback&&callback()
  callback?.()
}

fn()